Wayville’s Groovin The Moo (26 April) was ground zero for the Billie-mania explosion, a pop culture phenomenon akin to Nirvana, as Dave Grohl said, or the Fab Four, and she’s just getting started.

Teen superstar Billie Eilish remembers her last visit to Adelaide well, and for all the wrong reasons. On a scorching afternoon at Port Adelaide’s Harts Mill, a then 15-year-old Billie battled horrific technical difficulties during her Laneway Festival set, which was streaming live nationally on Triple J.

Back then, not even a malfunctioning mic could hold her back. Just two years later, the afternoon sets are a distant memory; Billie is a headliner now, with the clout to banish photographers from the photo pit.

Who needs photographers anyway, when you have a frenzied mob of zennials wielding smartphones jockeying to be as close to their idol as physically possible, so they can Snapchat the experience to their jealous friends?

Billie is the voice of a new generation; she wasn’t born until after September 11; she never knew a world without mobile phones, the internet or the threat of climate change, and barely remembers a time without social media. She resonates with her followers like nobody else on the GTM line-up.

On a day where A$AP Twelvvy struggled in vain to get an A$AP shouted back at him from the crowd, Billie’s lyrics were screamed at such a volume that they drowned out the amplifiers. She hasn’t quite reached The Beatles at Shea Stadium levels yet, but give her a few years.

With so many in attendance either there to see Billie, or to chaperone their children so that they could see Billie, some renowned acts faced a tougher-than-usual task evoking a response from the punters.

Holy Holy delivered incendiary riffs to a smattering of applause. DMA'S Thomas Dell’s pure falsetto achingly drifted into the ether on ‘The End’, with the same response.

'90s icons Regurgitator knew the score though, as they always do. They joked about their age, trolled the crowd with a hint of Guns N Roses ‘Sweet Child Of Mine’ and politely educated the unacquainted that “this is a song about licking assholes”.

One group that didn’t need to introduce themselves - although they did anyway - was home-town heroes Hilltop Hoods. Playing their home turf for the first time in 2.5 years, the Hoods drew a universal response that translated across generations.

Joined by Ecca Vandal and local vocalist Nyassa, in her second ever live show, the Hoods blazed their way through all the hits, from ‘Nosebleed Section’ to ‘Exit Sign’ and culminating with ‘Cosby Sweater’.

Baby boomers danced along in the Udder Mayhem section, zennials had their hands up in the pit, and there was scarcely a free space to be found in either section. The Hoods got the party started, thankfully, after what can only be described as a train-wreck performance by one-hit-wonder Coolio. Think Meatloaf at the AFL Grand Final.

The ageing rapper must not have gotten the memo that it was an all-ages gig, as he asked “are you as high as I am?", before fumbling his way through the one song that we were all dying to hear, ‘Gangsta’s Paradise'.